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排序方式: 共有19条查询结果,搜索用时 15 毫秒
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In this study, we present an approach based on neural networks, as an alternative to the ordinary least squares method, to describe the relation between the dependent and independent variables. It has been suggested to construct a model to describe the relation between dependent and independent variables as an alternative to the ordinary least squares method. A new model, which contains the month and number of payments, is proposed based on real data to determine total claim amounts in insurance as an alternative to the model suggested by Rousseeuw et al. (1984) [Rousseeuw, P., Daniels, B., Leroy, A., 1984. Applying robust regression to insurance. Insurance: Math. Econom. 3, 67–72] in view of an insurer.  相似文献   
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We are investigating the use of capacitive micromachined ultrasonic transducers (cMUT's) for use in medical imaging. We propose an ultrasound probe architecture designed to provide volumetric ultrasound imaging from within an endoscope channel. A complete automated experimental system has been implemented for testing the imaging performance of cMUT arrays. This PC-based system includes custom-designed circuit boards, a software interface, and resolution test phantoms. We have already fabricated 1D and 2D cMUT arrays, and tested the pulse-echo imaging characteristics of 1D arrays. Beamforming and image formation algorithms that aim to reduce the complexity of data acquisition hardware are tested via numerical simulations and using real data acquired from our system.  相似文献   
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The pK a values of cefdinir and cefixime, which are used in the treatment of bacterial infections, have been determined precisely in water and methanol?Cwater binary mixtures (20% v/v) using spectrophotometric titration and LC, respectively. A simple, fast and precise isocratic high-performance liquid chromatographic (LC) procedure has been developed for the determination of cefdinir and cefixime in drug formulations. This method was validated successfully for specificity, precision, linearity, range, accuracy, limit of detection, and limit of quantitation as per the ICH guidelines. The proposed method can be used for routine analysis of studied cephalosporin compounds and as an alternative tool for drug quality control laboratories.  相似文献   
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Flow behaviors around permeable cylinders were investigated using Particle Image Velocimetry technique in deep water. The height of deep water and free stream velocity were kept constant as hw = 340 mm and U = 156 mm/s. To find out the effect of the permeable cylinders on the flow structure, eight different porosities (β = 0.4, 0.5, 0.6, 0.65, 0.7, 0.75, 0.8, and 0.85) were used. The results have indicated that the permeable cylinders are effective on the control of large-scale vortical structures downstream of the permeable cylinder. As the porosity increases, turbulent kinetic energy and Reynolds shear stress decrease. This means that the fluctuations in the wake region are significantly weakened by permeable cylinders. The permeable cylinders having the porosity higher than 0.6 do not pose an obstacle in the flow. Furthermore, for all diameter values of permeable cylinders, it can be concluded that the flow structures downstream of the permeable cylinder show similar trend with each other.  相似文献   
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SUMMARY: Visualization of enlarged laryngeal lesions is the most important factor in choosing a surgical technique, especially for partial surgery. For this reason standard microlaryngoscopy, a computed tomography (CT) scan of the larynx, and 30 degrees telescopic microlaryngoscopy were compared during evaluation of the laryngeal ventricul and sub-glottic area. The histopatholgoical findings of the specimens collected under each modality were simultaneously compared. Comparison of the histopathological findings, which corresponded to inspection with the 30 degrees telescopic method, was more significant than with the use of standard microlaryngoscopy or the CT scan. The aim of the current study therefore was to determine the importance of the 30 degrees telescopic microlaryngoscopic method for the evaluation of the laryngeal ventricle and subglottic area.  相似文献   
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Polyphenolic acids are a complex group of compounds that have attracted enormous attention in the last few years because of their biological properties. In this work, the proportion of organic modifier and the pH of acetonitrile-water mixtures used as mobile phases were optimized in order to separate a series of polyphenolic compounds. The linear solvation energy relationship formalism based on the single solvent polarity parameter, E(T)N was used to predict their chromatographic behavior as a function of the percentage of acetonitrile in the eluent. Moreover, the correlation established between retention and the pH of the aqueous-organic mobile phase was used to optimize the pH of the mobile phase. The optimized mobile phase is composed of acetonitrile and formic acid buffer adjusted to pH 4.25, with 12% (v/v) acetonitrile. Also, the pKa values of polyphenolic acids in acetonitrile-water mixtures were determined using chromatographic data, and in order to validate the optimized conditions, a series of polyphenolic compounds was studied in strawberries.  相似文献   
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Cobalt ferrite (CoFe2O4) spinel has been found to produce C2−C4 hydrocarbons in a single-step, ambient-pressure, photocatalytic hydrogenation of CO2 with a rate of 1.1 mmol g−1 h−1, selectivity of 29.8 % and conversion yield of 12.9 %. On stream the CoFe2O4 reconstructs to a CoFe−CoFe2O4 alloy-spinel nanocomposite which facilitates the light-assisted transformation of CO2 to CO and hydrogenation of the CO to C2−C4 hydrocarbons. Promising results obtained from a laboratory demonstrator bode well for the development of a solar hydrocarbon pilot refinery.  相似文献   
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Abstract

Graft polymerization of acrylamide (AAm) on 1, 1, 2, 2 tetrachloro-ethane (TCE) preswelled poly(ethylene terephthalate) (PET) films were performed with chemical initiation method using asobisiso-butyronitrile (AIBN) initiator. Temperature was found to have a greater effect on the swelling then the swelling time. Variation of the graft yield with polymerization temperature, time, AIBN concentration, AAm concentration, AIBN and AAm inclusion times were investigated. The optimum temperature for grafting was found to be 70°CC. The graft yield was observed to increase with polymerization time, AAm concentration, initiator and monomer diffusion time up to a saturation graft yield and then leveled off. An increase in AIBN concentration first enhanced the percent grafting then showed a decrease. The addition of some salts (Ni2+, Cr3+, Co2+, Cu2+) on the rate of grafting was also investigated. From the temperature dependence of the initial rate of grafting, the overall activation energy was found to be 4. 1 kcal/mol and relevant rate equation have been derived. The effect of grafting on film propities, such as water absorption capacity, intrinsic viscosity were determined. Grafted films were characterized by FTIR spectros-copy and scanning electron microscopy (SEM).  相似文献   
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